The present disclosure relates to a hydrostatic test device and a hydrostatic test method for a high pressure turbine, and more particularly to a hydrostatic test device capable of testing or inspecting the structural stability of a casing surrounding a rotor of a steam turbine.
In general, a steam turbine has a structure that allows high pressure and high temperature steam, which is generated from a steam generator, such as a boiler, a heat recovery steam generator (HRSG), or a nuclear reactor, to collide with a turbine blade, thereby rotating a shaft by an impulse or a reaction of the turbine blade.
The steam turbine includes a steam inlet pipe that supplies steam, a high pressure casing that surrounds a rotor and blade rotated by the steam, a last stage blade (LSB), and a lower pressure casing that surrounds a diaphragm. In addition, the high pressure casing is coupled to a main steam inlet to introduce the high temperature and high pressure steam into the high pressure casing, and a main steam entrance is formed in the high pressure casing to couple the main steam inlet to the high pressure casing.
The high pressure casing, which is a pressure vessel that maintains internal pressure (HP) and vacuum pressure (LP), is a structure that supports and protects internal parts. In addition, the high pressure casing guides steam discharged from a main steam pipe.
To this end, the high pressure casing is formed therein with a plurality of feeding holes corresponding to the main steam pipe and a plurality of high pressure (HP) inlets.
Since the high pressure casing is used under high temperature and high pressure operating conditions as described above, the high pressure casing is formed of a thick casting, and has a structure in which an upper casing is coupled to a lower casing.
In addition, since the high pressure casing is used under high temperature and high pressure conditions, the high pressure casing is subject to a hydrostatic test in order to determine if the high pressure casing has the strength to withstand pressure about 15 times greater than operating pressure.
For the hydrostatic test of the high pressure casing, a cylindrical sealing member (or cylinder) is fixedly inserted into a feeding hole of the upper and lower casings and a plurality of pipes are fixed between the upper and lower casings so that the sealing member is not out of the space between the upper and lower casings.
In other words, the pipes are fixedly supported between the upper and lower casings formed therein with the feeding hole, that is, a main steam inlet.
In addition, a circular-shaped plate is fixed to an inner part of the casing to partition the inner part of the casing into a plurality of spaces for water pressure to be measured. Further, the plates are fixed to form spaces having various water pressures to be measured.
Water is fed into the partitioned space (e.g., chamber) to test for water leakage, air tightness, and pressure.
After the sealing member (or cylinder) is fixed into each main stream inlet so that the main stream inlet is sealed, the hydrostatic test is performed at about 250 kgf/cm2.
For example, a hydrostatic test device for a high pressure turbine, in which a plurality of plates, which are spaced apart from each other by a predetermined distance, are provided in a case, and water is fed to a chamber formed between the plates to perform a water pressure test. The hydrostatic test device includes a first water feeding hose formed through the plate so that water is fed to a relevant chamber from an outside, second and third water feeding hoses connected through a case so that water is fed to the plate of the relevant chamber through one chamber, first and second air discharge hoses communicating with each other through the plate so that air existing in the relevant chamber is discharged out, and a third air discharge hose passing through the case so that the air is discharged out in the state that the third air discharge hose communicates with the relevant chamber.
However, according to the hydrostatic test device for the high pressure turbine of the related art, since the sealing member, which seals the main steal inlet, does not independently seal the main seal inlet, the pipe, which fixes the sealing member into the casing, must be additionally fixed into the casing. Since the pipe is a heavy object having a long length of 3 m to 4 m, the pipe is difficult to handle, and working time may be increased.
In addition, the pipe is inclined in the casing during the hydrostatic test, so that the sealing member may not be fixed. Accordingly, an exact hydrostatic test result cannot be obtained. In addition, since the upper and lower casings must be disassembled from each other and assembled with each other again in order to fix the inclined pipe, working time may be increased.
Further, the pipe is moved in the casing during the hydrostatic test, so that the sealing member may be moved. Accordingly, the water pressure is not uniformly maintained, but changed in a hydrostatic test region, so that the reliability of the hydrostatic test may be degraded.